Our lab has recently identified a novel and functional RNA ligase in the bacterium Deinococcus radiodurans. Because homologous proteins can be found in several other organisms, we anticipate the finding of this research to translate to a broader biological phenomenon. Additionally, the gene encoding the Deinococcus RNA ligase on which this study focuses is located adjacent to other putative RNA repair pathway members. In the course of my proposed research I will carefull yexamine the substrate requirements for this new enzyme, determine the role of a novel domain that is conserved across genera but of unknown function, and identify residues that contribute to catalysis, as well as characterize the nature of their contributions. In addition to these in vitro experiments, I will also examine the role of this RNA ligase in vivo and use X-ray crystallography to determine the native structure. [unreadable] [unreadable]